mhi: core: Separate rddm support and dump collection

As of now, there is no way for MHI to know if device supports RDDM
and host controller wishes to skip ramdump collection. Allow for
that by letting the controller set the rddm support boolean which
indicates device side support. If rddm_size is set to zero while
the support for RDDM is present, that indicates disinterest in
ramdump collection if RDDM execution environment is entered.

Change-Id: I0a36219fc7782951aa1b81b9ec0d182ecfb3a916
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>